Is Intermittent Fasting the Key to Longevity?

Intermittent fasting is not only good for the waistline, but studies find it may play a role in staving off the degenerative effects of aging.

This path to greater longevity begins when one has fasted for twelve or more hours (more commonly 14 -16 hours), which flips an important metabolic switch that cues the body to burn molecules known as ketones instead of glucose as fuel.

Ketones then talk to the brain, telling it to release another crucial molecule called brain-derived neurotrophic factor (BDNF) that builds and strengthens the neural connections in areas of the brain responsible for learning and memory (key areas of decline as we age).

According to Dr. Walter Longo, in an interview with CNN, one of the ways ketones offer protections against disease and aging is that they appear to reduce the numbers of damaged white blood cells in the blood stream. Then, when you eat again after fasting, the body regenerates newer, healthier cells. You can think of fasting as getting rid of the “junk” and allowing the body to replace damaged cells with new ones, he explained.

To test longevity effects of calorie restriction on male mice, researchers from the National Institute on Aging (NIA), the University of Wisconsin-Madison and the Pennington Biomedical Research Center in Louisiana split 292 mice into three groups, fed them slightly different foods, and fed one select group 30% fewer calories per day than the other two groups, and only once a day. The group of mice with prolonged feeding times lived longer, on average, than their more regularly fed peers. Not only that, but the calorie-restricted mice’s health benefits persisted no matter the number of calories they ate, or the food content.

Lead author Rafael de Cabo, Ph.D. told USA Today he believes that fasting puts the metabolism into “standby mode” and, echoing Dr. Longo, “removes all the garbage at this time.”

It’s not just mice, however. According to an article in Nature, “In mammals, caloric restriction consistently results in extended lifespan.”

Indeed, additional studies on the effects of caloric restriction in primates found that found rhesus monkeys eating a diet restricted by 30% for two-thirds of their lives had cells that looked approximately seven years younger than their actual age. The researchers suggest that caloric restriction has a positive impact on a process of aging, at the epigenetic level of DNA, known as “methylation drift” that gets worse as we age.

Another piece of the fasting-aging puzzle may be found in our intracellular powerhouses, our mitochondria.

In one 2017 study in the journal Cell, using the worm C. elegans, which only live two weeks and thus provide a good aging model, researchers found that dietary restriction had a profound effect on the worms’ mitochondria, the energy centers of cells. Changes in mitochondria — such as fragmenting and swelling — are considered hallmarks of aging across species, and thought to be linked to many age-related conditions ranging from Alzheimer’s to Parkinson’s disease.

Their research identified a molecule, known as AMP-activated protein kinase (AMPK), activated by dietary restriction, which keeps mitochondria healthy by preventing them from fragmenting, thus promoting longer lives in C. elegans.

Though there is a great deal yet to be understood in humans, studies have linked fasting to a number of improved health biomarkers related to longer life, such as lower cholesterol and blood pressure, and greater regulation of blood sugar levels.

While fasting won’t stop us from aging, it may be our best bet to slow it down.